GIANT-CELLS OF BONE-MARROW 309 
3. The giant-cells in normal marrow and in the yolk-sac are 
devoid of phagocytic function. The presence of polymor- 
phonucleated granulocytes of the special eosinophilic variety 
in greater or less abundance within the cytoplasm do not signify 
intracellular differentiation nor phagocytic ingestion, but are to 
be interpreted as secondary passive invasions due to the rela- 
tively less resistant character of the giant-cell cytoplasm as 
compared with the general marrow parenchyma against the 
pressure exerted by an area of actively proliferating leucocytes, 
or as active invasions by special polymorphonucleated phago- 
cytes of a disintegrating cytoplasm. 
4. The giant cells do not undergo mitosis, either complete 
cytoplasmic or incomplete nuclear. The groups of chromatic 
particles simulating plates of chromosomes of multipolar spindles 
of pathologic tissues are simply chance aggregations of chroma- 
tin during the degenerative process. These aggregations are 
not accompanied by archoplasmic fibers. They represent 
terminal stages in the several modes of degeneration of the 
polymorphonucleated and multinucleated varieties of giant-cells. 
5. The lobulation and direct division of the giant-cell nucleus: 
the accompanying partition of the centrosome into a_pluri- 
corpuscular element; the later dissolution of the nuclei and the 
formation of chromatin masses and groups of such masses: and 
the coincident production of blood-platelets from the cytoplasm, 
first by segmentation of pseudopods and later by mass fragmen- 
tation of larger cytoplasmic areas, are all to be interpreted in 
terms of the action of some common unknown factor working 
toward the eventual disintegration of these cells. 
6. There is no adequate evidence to support the claim that the 
hemogenic giant-cells of red bone-marrow have a phagocytic 
function, or that a genuine mitotic mechanism underlies the 
increase in complexity or the segmentation of the polymorphous 
nucleus. Once having passed beyond the stage with features 
characteristic of the hemoblast, their further history only leads 
through progressive steps toward disintegration, involving 
terminally in some cases nuclear appearances simulating multi- 
polar mitotic figures. 
